Third generation partnership project (3GPP) mobile communication systems based on a wideband code division multiple access (WCDMA) radio access technology are widely spread all over the world. High-speed downlink packet access (HSDPA) that can be defined as a first evolutionary stage of WCDMA provides 3GPP with a radio access technique that is highly competitive in the mid-term future. However, since requirements and expectations of users and service providers are continuously increased and developments of competing radio access techniques are continuously in progress, new technical evolutions in 3GPP are required to secure competitiveness in the future.
An orthogonal frequency division multiplexing (OFDM) system capable of reducing inter-symbol interference with a low complexity is taken into consideration as one of next generation (after the third generation) systems. In the OFDM system, serial input data symbols are converted into N parallel data symbols and are carried and transmitted on separate N subcarriers. The subcarriers maintain orthogonality in a frequency dimension. Orthogonal channels experience mutually independent frequency selective fading. Inter-symbol interference can be minimized since intervals of transmitted symbols are lengthened. Orthogonal frequency division multiple access (OFDMA) is a multiple access scheme in which multiple access is achieved by independently providing some of available subcarriers to a plurality of users when using a system which employs the OFDM as a modulation scheme. In the OFDMA, frequency resources (i.e., subcarriers) are provided to the respective users, and the respective subcarriers are independently provided to the plurality of users. Thus, the subcarriers generally do not overlap with one another. Eventually, the frequency resources are mutually exclusively allocated to the respective users.
In order to implement various transmission or reception methods to achieve high-speed packet transmission, transmission of a control signal on time, spatial, and frequency domains is an essential and indispensable factor. A channel for transmitting the control signal is referred to as a control channel. A physical layer channel for transmitting control information from a base station (BS) to a user equipment (UE) is referred to as a physical downlink control channel (PDCCH). A physical layer channel for transmitting control information from the UE to the BS is referred to as a physical uplink control channel (PUCCH). The control information transmitted through the PUCCH may be various, e.g., an acknowledgement (ACK)/negative-acknowledgement (NACK) signal which is a response for downlink data transmission, a channel quality indicator (CQI) indicating downlink channel quality, a scheduling request signal for requesting allocation of radio resources, a multiple input multiple output (MIMO) control signal that is multiple antenna related information, etc.
The scheduling request signal is a message used when the UE requests the BS to allocate radio resources for uplink data or downlink data transmission. The BS allocates the radio resources to the UE upon receiving the scheduling request signal from the UE. A scheduling gain can be obtained when the BS can know further detailed information on data required by the UE rather than determining whether the radio resources are allocated according to only a presence/absence of the scheduling request signal.
Accordingly, there is a need for a method of transmitting a scheduling request signal capable of representing a variety of control information.